This invention relates to railway safety equipment, namely, derails which are commonly used for derailing railed vehicles including locomotives, railroad cars and the like, which may be undesirably moving along railroad tracks, normally at a relatively low speed. There are many types of derails, known in the rail industry, which have been used for many years. Certain types of derails are substantially permanently fixed to one rail of a pair of railroad track rails and various methods may be used to move the derail between an operative position and an inoperative position. Some derails are relatively light in weight so as to be portable and are not movable between operative and inoperative positions.
At least in connection with certain types of derails, the railway industry historically required that the highest point of a derail was not to be higher than four inches measured from the top of the rail upon which the derail was affixed. A principal reason for this requirement was that the pilot (sometimes called a “cowcatcher”) of a railway locomotive must be allowed to clear the highest point of the derail so that a heavy locomotive's pilot did not sweep, push or knock off the entire derail when the locomotive was undesirably moving at a relatively low speed, such as up to 10 miles per hour. If the derail is moved out of derailing position by the pilot, the derail becomes ineffective and the undesirably moving locomotive may cause serious damage to other locomotives or railway cars, such as at a railroad yard, or even cause serious injury or death to railway workers in the area.
Relatively recently, the railway industry changed its standards to require that certain derails could not have its highest point more than three inches above the upper surface of a railroad rail upon which the derail is affixed. In essence, certain existing derails higher than or just at three inches above the rail could be unsafe to use, particularly in connection with undesirably moving heavy locomotives, because the entire derail could be forced off the track by the pilot of the locomotive before the lead wheel of the undesirably moving locomotive could be engaged by the derail, thereby causing the undesirably moving locomotive to continue moving unsafely rather than allowing the derail to remain in place and cause a safe derailment of the locomotive if needed.